Self-propelled road vehicle



y 1, 1933. E. T. J. TAPP ET AL 9 SELF PROPELLED ROAD vsmcm:

Fil ed April ,10, 1931 HTTORNEY.

l atentecl July 11 1933 UNITED STATES SELF-PROPELLED RoAD VEHICLE" Application filed April 10, 1931, Serial No. 529,144, and in Great Britain April 17,1930.

This invention relates to road vehicles propelled by more than one axle of the bevel gear driven type and wherein the forward of two driving axles isso constructed to accommodate a driven bevel pinion in addition to the normal driving pinion, said driven pinion deriving power from the driving pinion by two bevel wheels meshing with both driving and driven pinions.

The object of this invention is to provide an improved construction of driving mechanism of the above mentioned type whereby stress in the teeth and bearings of the con-,

structions are considerably reduced.

According to this invention, both bevel wheels are mounted on the differential cage, one being rigidly fixed to the'said cage and the other free to revolve on it, thusenabling both driving and driven pinions to transmit and receive power on both sides and consequently share the loadof adouble number of teeth, and reduce the stresses inconsequence.

Itwill be seen that the loads on the bearings supporting the differential cage are reduced by virtue of the fact that the upward climbing tendency of the pinion on one bevel wheel will be neutralized, or partially so, by its downward climbing tendency on the other.

The said free bevel wheel is preferably carried on a sleeve extending over and surrounding the cage containing the differential gear, the said sleeve being as long as can be conveniently made and extending as close to the fixed wheel as possible, one bearing being placed in or on one extremity of the sleeve and another bearing on or in the other extremity.

One of these hearings may also be capable of taking thrust load of the free wheel away from the bevel pinions. In some constructions the sleeve may be of sufiicient length to form a suitable bearing and the said second bearing being omitted, in which case, a separate thrust bearing must be provided.

In one convenient construction, for instance, a plain bearing may be formed in or on the sleeve and a combined thrust and journal ball roller bearing placed at the outer ex-.

tremity of the sleeve to which the free wheel PATENT oFFIc ERNEST THOMAS JAMES TAP]? AND PERCY JOHN RUTTY TAPP, or mmmzmetmn sleeveacting more as a steadying means and carrying only a light load, which since the bearing area afforded by the large diameter of the cage is subject to very little Wear.

Since both crown wheels are entirely and completely supported in the axle casing by the bearings which carry the difl'erential cage, no additional strain is imposed on the sa d casing and theopposing driving forces of the two bevel or crown wheels reduces thestresses actuallyimposed on the said bear ing supporting the cage.

It is preferable that a smallamount'of side float be permitted in the cage relativeto the V pinions or vice versa, this side play being obings supporting the differential cage, by a tained either by sidetolerance in the bear sliding movement allowed in or on the bear ings, or alternatively one of the pinions may be allowed to float slightly,

Referring now to the accompanying draw-' ing, which is a sectional plan view of one form of driving mechanism constructed in accordance with this invention. c is the crown wheel meshing with the driving pinion and the driven pinion p The said crownwheel is suitably mounted on the cage e carrying the differential gear for'the centre axle. I

b is the additional bevel wheel whichis carried onthe-s'leeve s mounted on two beajlrings Z, i, surrounding the exterior of the cage 6. The bearing Z is a combined thrust and journal ball bearing and z' is a plain bearing. The bearing Z is disposed closer in line With the teeth of the bevel wheel 7) and takes the major portion of the load. The bearing 2' takes a smallerload, the reason for this arrangement being that, owing to the construction there is very little space for a bearing at the end of the sleeve 8 where the bearing i 1s shewn, owing to the proximity of the bevel pinion shafts and bearings. I

The sleeve 8, it will be noticed, is specially contoured so as to allow clearance where the extra bevel wheejl.

shaft protrudes at t from the said bearing, .and a smaller strengthening rib r on the end of the sleeve 8 to stifien it since there is no room for great thickness throughout its length.

Where the bearing Z is placed, however, more room. is available, owing to the cage be. ing reduced at thispoint.

In order to make up the difference between the inside diameter; of the bearing and the outside diameter of the cage "at this point, a bush or collar is used, and is prevented from moving laterally under the side thrust of the bevel wheelby being placed to abut against the inner ring of the bearing '9", which isin turn retained by the flangedring nut n screwed -into theend ofthe differential cage. Adjusting washers may, if; necessary, be placed between the said bushk and the in- .ner rin of the bearin 1n order to var.

slightly the actual position ofithebush lc' to obtain correct mesh of the additional wheel with the'bevel pinions. A smaller bearing may, of course,be used in :place of], and the bush is -omitted. v V v v The reason for mounting the bevel wheel I);

on the dilierential cage 6 is in order toreduce' the loads on the bearings supporting the diL ferential cage, since the pressure on the crown Wheel 0 away from the pinion, due to the drive, will normally cause a thrust on. the bearing 9 which is here shownto be of the taper roller type.

The bevel wheel Z) howevejnalso has a cor- "responding thrust away from the bevel .pi-n

ion andthis being transmitted -tothe-cage by the ball bearing Z, neutralizes, or partially so, the thrust already referred to.

Itwill also be seen that the journal loads '0I1 the bearings gand 9 carrying the cage,

arealso relieved in as much as the upward or downward pressure of. the crown wheel will be neutralized, or partiallyYso, by r-the inverse -upward or downward pressure of the ion bearings will also be reduced for the same aso a What we claim is V I 1. Ina differential drive mechanism, a difierential cage,;a driving axleextending natures;

tate upon "said cage, and a combined thrust and journal bearing supportingsaid sleeve at its outer end.

2. In. a differential drive mechanism, a

ditl'erential cage, a driving axle extending a from said 'ca ge, bevel driving pinion, a bevel driven pinion for the purpose of conveying powe-r-fto a second driving aX-le, a pair of bevel wheels mounted on the differential cage and nie'shingwith both I driving and driven pin-ions, one'of sai d wheels being r-i idly fixed to said cage to rotate therewith, a sleeve extending over-and surrounding thediiierential cage and carrying the other, of said wheels whereby the s'ame may be free to rotate upon said cage, andga thrustbearing supporting said sleeve at its outer end, said thrust hearing abutting direct against the bearing POP: tion of the differential cage, 7

- In j axliliE'erentiaL drive t-mecha'nism, a differential cage, adriving axle extend-ing from said cage, fa bevel driving :pinion, ar

bevel driven ,pinion for the purpose of conveyingpower to the second driving axle, a pair of bevel wheels mounted on tllG-jdlf: ferential cage and meshing with both driving and driven .pinio'ns, oneof said wheels being'rigidly fixed to saidcage to rotate there with-,fa slee ve extending -over and surrounding the difl'ei' ential cage and carrying the other-of said wheels whereby the same maybe free to rotate upon said cage, :a thrust hearing supporting said sleeve at;its FOu'ter end, and means "between said thrust 'bearingfand j j A r the inner bearing portion of the differential The loads on the driv1ngand-jdriven pincage whereby to prevent lateral movement of;said-thrustbearing. j In testimony whereof {they-affix their sig ERNEST AMES, TA-PP. 1 PERCYJOHN RUITY T-APP. 

